Insect offspring devouring core of rising taproot (8)
I believe the answer is:
scorpion
'insect' is the definition.
(thesaurus)
'offspring devouring core of rising taproot' is the wordplay.
'offspring' becomes 'scion' (scion can mean a descendant of a rich family).
'devouring' means one lot of letters goes inside another.
'core of' means to look at the middle letters.
'rising' becomes 'tor' (I've seen this before).
'taproot' becomes 'rp' (I can't justify this - if you can you should believe this answer much more).
The centre of 'tor' is 'o'.
'o'+'rp'='orp'
'scion' enclosing 'orp' is 'SCORPION'.
(Other definitions for scorpion that I've seen before include "Kind of arachnid with pincers and stinging tail" , "Venemous creature" , "Stinging creature" , "Animal with a sting in its tail" , "Eight sign of Zodiac, kind of spider" .)